The advances of developmental biology are beginning to unravel the mechanisms behind congenital anomalies and should, in the not too distant future, have an impact upon their treatment. Much of classic developmental biology represents careful descriptions of the developing body form, in this case the upper limb. There is a great deal to be learned from this approach. More recent experimental manipulations of limb development are serving to establish the basic processes by which form is generated in each cycle of life. Such experimental manipulations might also be regarded as potential prototypes for surgical interventions of the future.